WO2009066070A1 - A connector for a composite tubular shaft - Google Patents
A connector for a composite tubular shaft Download PDFInfo
- Publication number
- WO2009066070A1 WO2009066070A1 PCT/GB2008/003886 GB2008003886W WO2009066070A1 WO 2009066070 A1 WO2009066070 A1 WO 2009066070A1 GB 2008003886 W GB2008003886 W GB 2008003886W WO 2009066070 A1 WO2009066070 A1 WO 2009066070A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- nut
- composite
- connector
- collar
- tube
- Prior art date
Links
- 239000002131 composite material Substances 0.000 title claims abstract description 84
- 238000000034 method Methods 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 230000005540 biological transmission Effects 0.000 claims description 2
- 239000000835 fiber Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 238000011068 loading method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 230000036316 preload Effects 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- VXHYVVAUHMGCEX-UHFFFAOYSA-N 2-(2-hydroxyphenoxy)phenol Chemical compound OC1=CC=CC=C1OC1=CC=CC=C1O VXHYVVAUHMGCEX-UHFFFAOYSA-N 0.000 description 1
- IISBACLAFKSPIT-UHFFFAOYSA-N Bisphenol A Natural products C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009730 filament winding Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C7/00—Connecting-rods or like links pivoted at both ends; Construction of connecting-rod heads
- F16C7/02—Constructions of connecting-rods with constant length
- F16C7/026—Constructions of connecting-rods with constant length made of fibre reinforced resin
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C3/00—Shafts; Axles; Cranks; Eccentrics
- F16C3/02—Shafts; Axles
- F16C3/026—Shafts made of fibre reinforced resin
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C7/00—Connecting-rods or like links pivoted at both ends; Construction of connecting-rod heads
- F16C7/06—Adjustable connecting-rods
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D1/00—Couplings for rigidly connecting two coaxial shafts or other movable machine elements
- F16D1/06—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for attachment of a member on a shaft or on a shaft-end
- F16D1/08—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for attachment of a member on a shaft or on a shaft-end with clamping hub; with hub and longitudinal key
- F16D1/0847—Couplings for rigidly connecting two coaxial shafts or other movable machine elements for attachment of a member on a shaft or on a shaft-end with clamping hub; with hub and longitudinal key with radial clamping due to a radial screw
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D1/00—Couplings for rigidly connecting two coaxial shafts or other movable machine elements
- F16D1/10—Quick-acting couplings in which the parts are connected by simply bringing them together axially
- F16D1/108—Quick-acting couplings in which the parts are connected by simply bringing them together axially having retaining means rotating with the coupling and acting by interengaging parts, i.e. positive coupling
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
- Y10T29/49947—Assembling or joining by applying separate fastener
- Y10T29/49963—Threaded fastener
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T403/00—Joints and connections
- Y10T403/47—Molded joint
- Y10T403/471—And independent connection
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T74/00—Machine element or mechanism
- Y10T74/20—Control lever and linkage systems
- Y10T74/20012—Multiple controlled elements
- Y10T74/20018—Transmission control
- Y10T74/20177—Particular element [e.g., shift fork, template, etc.]
Definitions
- This invention relates to a connector for mechanically joining a composite tubular shaft to another component and which permits the transfer of axial loads between the shaft and component.
- Composites are becoming more widely recognized as a viable solution to a range of applications due to their inherent strength to weight ratio, and the ability to more accurately analyze the composite structure at the design phase.
- Composite tubular structures are currently applied in many fields, for example, motor sport, aerospace and medical. In use, composite tubular structures may be subjected to axial tensile and compressive loads, bending and torsional loadings. With increasing demand to transmit the working load directly through to the composite structure comes a requirement to design a suitable composite to end fitting or connector.
- the connector is required to connect the composite tubular structure to another component in such a way that the load path is optimised to the behaviour of the composite element. In high performance situations the connection device employed will ideally be designed such that it does not damage the composite matrix during assembly or usage.
- connection device and subsequent joint between the composite and surrounding structure will be stronger than the composite tubular structure itself.
- a known joint for transmitting axial loads to composite tubular structures is shown in US5082 314 and comprises an annular band embedded in the external surface of the tube and end cap which connects to the band.
- a connector for connecting a composite tube, tubular rod or shaft to another component which comprises a screw threaded nut the outer surface of which is shaped to receive in use composite material applied around the nut in a green state during tube manufacture, an annular collar for placement over the nut and composite material, a screw threaded end fitting which engages the screw thread within the nut, and a load means in use axially moving the collar relative to the end fitting to exert a clamping load onto the composite material surrounding the nut.
- the connector may be utilised with different composite matrices.
- the fibre alignment in a composite structure may be uni-directional or multiaxial and therefore manufactured by composite stitching, lay-up, filament winding or any other process for producing the composite element.
- the composite structure can also be produced from any fibre and matrix although typical choices are carbon or glass for the fibre, and thermoset or thermoplastic polymers for the matrix.
- the material of the connector may be determined by the nature and magnitude of the desired load case and environmental conditions. That is to say that all engineering materials are open for consideration including metals, polymers, fibres and ceramics. The manufacturing technique for the end fittings will subsequently be determined by the selected material, annual volumes and required dimensional accuracy.
- the connector is formed from stainless steel.
- the connector Since the composite tube is clamped between the nut and external collar the connector is particularly suitable for transmitting axial compressive and tensile loads. There is no need for adhesives or rivets to transfer the loads from the surfaces of the metal components to the surface of the composite tube - it all relies on the mechanical action where the nut is pulled while the collar is pushed, thereby generating the clamping load on the composite.
- the clamping load is always of greater magnitude than the axial tensile or compressive loads that the system is under and therefore there is no relative movement between the surfaces of the composite and the metal nut or collar which could cause fretting fatigue failure.
- the design can be adopted to a tubular structure subjected to any combination of axial, bending and torsional loads, depending upon the specific design and package requirements.
- the external surface of the nut is substantially ovoid, more preferably comprising two back to back frustoconical surfaces so that the composite is flared outwards, then tapered inwardly (as measured radially from the axis of the tubular structure ) so as to create a feature to securely clamp against.
- the frustoconical surfaces may be roughened to increase frictional resistance to rotational movement between the nut and tubular composite.
- the end fitting may be provided with an annular flange and the load means acts between the flange and the collar to exert the clamping load on the composite tube.
- the load means comprise a plurality of circumferentially spaced screw means acting between the flange and collar.
- the screw means are bolts or screws mounted on the flange and which abut the collar.
- the clamp force is generated by rotation of the screws to further increase the axial spacing of the flange from the collar, i.e. the flange pulls the threaded nut while pushing the collar, thereby generating a clamping force on the composite between the collar and the nut.
- the clamping force on the composite ensures there is no relative movement between the surfaces of the composite and the nut or collar which could be a cause of fatigue failure by fretting.
- the invention further comprises a composite tube having a connector in accordance with the first aspect of the present invention fitted to at least one end thereof, the nut being incorporated into end of the tube.
- a composite control rod comprising a composite tubular body having an end connector, according to the first aspect of the invention ⁇ fixed to at least one end of the control rod for the transmission of compressive and tensile loads along the rod, the nut being incorporated within an end portion of the composite tubular body.
- the control rod may be provided with an end connector fixed at each end of the rod.
- the clamping load exerted on the composite tube between the nut and external collar may be greater than the tensile and compressive loads to be transmitted along the control shaft in use.
- the overall length of the control rod may be adjusted by releasing the clamping load and screwing the end fitting in one direction or the other to reposition the end fitting relative to the nut, and then re-applying the clamping load.
- Yet another aspect of the invention provides a method of attachment of a load transmitting connector to at least one end of tubular composite tube, rod or shaft wherein in said method there is provided a connector comprising a screw threaded nut the outer surface of which is shaped to receive in use composite, an annular collar, a screw threaded end fitting for engaging the screw thread within the nut, and a load means in use axially moving the end-fitting relative to the collar and exerting a clamping load said one end, wherein the nut is incorporated within said one end of the tube during tube manufacture, the tube is cured with the nut insitu, the annular collar is placed over said one end, the end fitting is screwed into the nut, and the load means is operated to move the end fitting relative to the collar and clamp said end of the composite tube between the collar and nut.
- the clamping load exerted on the composite tube may be varied as is desired for the particular end use of the control rod.
- the end of the tube is releasably clamped allowing the end fitting to be adjustably displaced relative to the nut.
- Fig. 1 is a longitudinal cross-section through one end of a composite tube having mounted thereon a connector according to the present invention
- Fig. 2 is an isometric sectional view of the tube and connector shown in Fig.1 , and
- Fig. 3 is a side elevation of the control shaft having a connector at each end.
- the control shaft 10 comprises a composite shaft 11 with a connector 13 fitted to one or both end portions 12.
- a typical control shaft 10 may be 600mm in length and the composite shaft 11 has a tubular construction having an outside diameter of about 66mm and an inner diameter of about 60mm.
- the connector 13 may be formed from stainless steel and includes a nut 14 which is incorporated within the end portion 12 of the tube 11 by having the composite material moulded, formed or wound around it during the manufacturing process. This will result in the nut 14 becoming an integral part of the composite structure which cannot be removed from the tubular structure without damage to the surrounding composite structure.
- the nut 14 is internally threaded and the external surface 18 is substantially ovoid comprising two back to back frustoconical surfaces 19, 21 so that the composite tube is flared outwards, then tapered inwardly (as measured radially from the axis A- A of the tubular structure) securely trapping the nut 14 within the end portion of the cured composite and creating a feature for clamping against.
- the frustoconical surfaces 19, 21 may be serrated or otherwise roughened to increase frictional resistance to rotational movement between the nut and tubular composite if desired.
- the shaft 11 is preferably formed from composite comprising carbon fibre with a resin matrix of an epoxy bisphenol A resin and an anhydride curing agent. Impregnated carbon tow is wound onto a mandrel in a plurality of layers with the nut 14 in place on the mandrel. The composite is then cured with the nut held in place. The volume fraction of carbon fibre in the composite is typically in the order of 65%.
- the connector 13 further includes an external annular collar 15 which is placed over the outside of the end portion 12 of the composite tube 11 and which in turn is held in place by an end fitting 16, which itself is screwed directly into the internal threaded nut 14, and a load means17 mounted on the end fitting 16.
- the collar 15 has a through bore 23 to accommodate the end fitting 16.
- the end portion 22 of the through bore 23 adjacent the composite tube 11 has an internal frustoconical surface which is substantially parallel with the tapered surface 21 on the nut 14.
- the nature of the tapered angles employed on the two opposed clamping surfaces of the external collar 15 and nut 14, preferably between 5° and 40° and more preferably between 10° and 25°, provides a clamp load to couple the connector to the end portion 12 of the composite structure and to transmit the working load through to the composite tubular structure 11.
- the taper and flare angles in the present example are 10°.
- the other end portion 24 of the through bore 23 comprises a larger diameter portion 24 forming an annular shoulder 25 within the collar 15.
- the end fitting 16 has an elongated screw threaded shank 20 which engages the nut 14 and is provided with a suitable manner of joint 26 for connection to a further component (not shown).
- the joint 26 is a diametral bore for accommodating a clevis pin, but any other suitable joint may be provided on the end fitting, for example the ball of a ball and socket joint, a universal joint etc..
- the end fitting 16 has a radially outwardly projecting annular flange 27 located midway along its length which has an axially extending cylindrical sidewall 28 thereon. The sidewall 28 extends away from the collar 15 and forms a cavity for housing the load means 17.
- the load means 17 comprises a plurality of set screws 29, preferably six but any number may be provided as is desired, mounted on the flange 27.
- the screws 29 are mounted in screw threaded holes 31 circumferentially spaced around the flange 27.
- the end fitting 16 when screwed into the nut 14 is locked in position by screwing the set screws 29 into abutment with the shoulder 25 and a clamping force is generated by rotation of the set screws to increase the axial spacing the flange 27 from the collar 15.
- Each screw is tightened in stages to a set torque load, in this example to about 15-16 kN.
- a suitable pre-load should be greater than the expected tensile and compressive loads to be transmitted through the control shaft.
- a suitable pre-load for the present control shaft/rod is about 80 kN .
- the control shaft 10 formed by the connectors 13 and composite tube 11 performs over a wide range of temperatures, from cryogenic to elevated and may form a control shaft of the type of the type used in aircraft wings for the operation of flaps.
- the control shaft 10 permits adjustment of its overall length. This is advantageous in use of the shaft 10 as the location of the fixed points within a surrounding component structure to which the shaft 10 may be mounted, will be subject to a certain tolerances.
- the length of adjustment within the assembled composite tube and connector is controlled by how far the screw threaded shank 20 of the end fittings 16 may be screwed into or out of the nut 14 Adjustment is permitted by slackening the screws 29. After adjustment to a desired length, the 'slack' left between the end fitting 16 and the external collar 15 is then taken up by the tensioning screws 29.
- a left hand thread may be provided at one end of the tubular structure, and a right hand thread at the other.
- the end fittings it will then be possible to rotate the composite tubular structure clockwise or anticlockwise to extend or contract the overall length of the shaft.
- the tensioning screws will be torqued up to take out any play rendering the assembly rigid and ready to take the designed loading.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Mutual Connection Of Rods And Tubes (AREA)
Abstract
A load transmitting connector (13) for composite tube (11) and a method of attachment of said connector (13) to the tube (11), the connector (13) comprising a screw threaded nut (14) having an outer surface (18) shaped to receive the composite, an annular collar (15), a screw threaded end fitting (16) for engaging the screw thread within the nut (14), and a load means (17), wherein the nut (14) is incorporated within said one end of the tube during tube manufacture, the tube (11) being cured with the nut insitu, the annular collar (15) is placed over said one end of the tube, the end (fitting 16) is screwed into the nut, and the load means (17) in use axially moving the end-fitting 16 relative to the collar (15) to exert a clamping load on the composite tube.
Description
A Connector for a Composite Tubular Shaft
Field
This invention relates to a connector for mechanically joining a composite tubular shaft to another component and which permits the transfer of axial loads between the shaft and component.
Background of the Invention
Composites are becoming more widely recognized as a viable solution to a range of applications due to their inherent strength to weight ratio, and the ability to more accurately analyze the composite structure at the design phase. Composite tubular structures are currently applied in many fields, for example, motor sport, aerospace and medical. In use, composite tubular structures may be subjected to axial tensile and compressive loads, bending and torsional loadings. With increasing demand to transmit the working load directly through to the composite structure comes a requirement to design a suitable composite to end fitting or connector. The connector is required to connect the composite tubular structure to another component in such a way that the load path is optimised to the behaviour of the composite element. In high performance situations the connection device employed will ideally be designed such that it does not damage the composite matrix during assembly or usage. Such connectors are shown in the applicants published Patents GB2424464B and GB 2435 317B. Ideally the connection device and subsequent joint between the composite and surrounding structure will be stronger than the composite tubular structure itself.
A known joint for transmitting axial loads to composite tubular structures is shown in US5082 314 and comprises an annular band embedded in the external surface of the tube and end cap which connects to the band.
Statements of Inventions
According to a first aspect of the present invention there is provided a connector for connecting a composite tube, tubular rod or shaft to another component and which comprises a screw threaded nut the outer surface of which is shaped to receive in use composite material applied around the nut in a green state during tube manufacture, an annular collar for placement over the nut and composite material, a screw threaded end fitting which engages the screw thread within the nut, and a load means in use axially moving the collar relative to the end fitting to exert a clamping load onto the composite material surrounding the nut.
The connector may be utilised with different composite matrices. The fibre alignment in a composite structure may be uni-directional or multiaxial and therefore manufactured by composite stitching, lay-up, filament winding or any other process for producing the composite element. The composite structure can also be produced from any fibre and matrix although typical choices are carbon or glass for the fibre, and thermoset or thermoplastic polymers for the matrix.
The material of the connector may be determined by the nature and magnitude of the desired load case and environmental conditions. That is to say that all engineering materials are open for consideration including metals, polymers, fibres and ceramics. The manufacturing technique for the end fittings will subsequently be determined by the selected material, annual volumes and required dimensional accuracy. Preferably the connector is formed from stainless steel.
Since the composite tube is clamped between the nut and external collar the connector is particularly suitable for transmitting axial compressive and tensile loads. There is no need for adhesives or rivets to transfer the loads from the surfaces of the metal components to the surface of the composite tube - it all relies on the mechanical action where the nut is pulled while the collar is pushed, thereby generating the clamping load on the composite. The clamping load is always of greater magnitude than the axial tensile or compressive loads that the system is under and therefore there is no relative movement between the surfaces of the composite and the metal nut or collar which could cause fretting fatigue failure. The design can be adopted to a tubular structure subjected to any combination of axial, bending and torsional loads, depending upon the specific design and package requirements.
Preferably, the external surface of the nut is substantially ovoid, more preferably comprising two back to back frustoconical surfaces so that the composite is flared
outwards, then tapered inwardly (as measured radially from the axis of the tubular structure ) so as to create a feature to securely clamp against. The frustoconical surfaces may be roughened to increase frictional resistance to rotational movement between the nut and tubular composite.
The end fitting may be provided with an annular flange and the load means acts between the flange and the collar to exert the clamping load on the composite tube.
The load means comprise a plurality of circumferentially spaced screw means acting between the flange and collar. Preferably the screw means are bolts or screws mounted on the flange and which abut the collar. The clamp force is generated by rotation of the screws to further increase the axial spacing of the flange from the collar, i.e. the flange pulls the threaded nut while pushing the collar, thereby generating a clamping force on the composite between the collar and the nut. The clamping force on the composite ensures there is no relative movement between the surfaces of the composite and the nut or collar which could be a cause of fatigue failure by fretting.
The invention further comprises a composite tube having a connector in accordance with the first aspect of the present invention fitted to at least one end thereof, the nut being incorporated into end of the tube.
Yet another aspect of the invention provides a composite control rod comprising a composite tubular body having an end connector, according to the first aspect of the invention^ fixed to at least one end of the control rod for the transmission of compressive and tensile loads along the rod, the nut being incorporated within an end portion of the composite tubular body. The control rod may be provided with an end connector fixed at each end of the rod.
The clamping load exerted on the composite tube between the nut and external collar, may be greater than the tensile and compressive loads to be transmitted along the control shaft in use.
The overall length of the control rod may be adjusted by releasing the clamping load and screwing the end fitting in one direction or the other to reposition the end fitting relative to the nut, and then re-applying the clamping load.
Yet another aspect of the invention provides a method of attachment of a load transmitting connector to at least one end of tubular composite tube, rod or shaft wherein in said method there is provided a connector comprising a screw threaded nut the outer surface of which is shaped to receive in use composite, an annular collar, a screw threaded end fitting for engaging the screw thread within the nut, and a load means in use axially moving the end-fitting relative to the collar and
exerting a clamping load said one end, wherein the nut is incorporated within said one end of the tube during tube manufacture, the tube is cured with the nut insitu, the annular collar is placed over said one end, the end fitting is screwed into the nut, and the load means is operated to move the end fitting relative to the collar and clamp said end of the composite tube between the collar and nut.
The clamping load exerted on the composite tube may be varied as is desired for the particular end use of the control rod.
The end of the tube is releasably clamped allowing the end fitting to be adjustably displaced relative to the nut.
Description of the Drawings.
The invention will be described by way of example and with reference to the accompanying drawings in which :
Fig. 1 is a longitudinal cross-section through one end of a composite tube having mounted thereon a connector according to the present invention, Fig. 2 is an isometric sectional view of the tube and connector shown in Fig.1 , and
Fig. 3 is a side elevation of the control shaft having a connector at each end.
Detailed Description of the Invention
Referring to Figures 1-3 of the drawings, there is shown a composite tubular control shaft or rod 10 according to the present invention. The control shaft 10 comprises a composite shaft 11 with a connector 13 fitted to one or both end portions 12. A typical control shaft 10 may be 600mm in length and the composite shaft 11 has a tubular construction having an outside diameter of about 66mm and an inner diameter of about 60mm. The connector 13 may be formed from stainless steel and includes a nut 14 which is incorporated within the end portion 12 of the tube 11 by having the composite material moulded, formed or wound around it during the manufacturing process. This will result in the nut 14 becoming an integral part of the composite structure which cannot be removed from the tubular structure without damage to the surrounding composite structure.
The nut 14 is internally threaded and the external surface 18 is substantially ovoid comprising two back to back frustoconical surfaces 19, 21 so that the composite tube is flared outwards, then tapered inwardly (as measured radially from the axis A- A of the tubular structure) securely trapping the nut 14 within the end portion of the cured composite and creating a feature for clamping against.
The frustoconical surfaces 19, 21 may be serrated or otherwise roughened to increase frictional resistance to rotational movement between the nut and tubular composite if desired.
The shaft 11 is preferably formed from composite comprising carbon fibre with a resin matrix of an epoxy bisphenol A resin and an anhydride curing agent. Impregnated carbon tow is wound onto a mandrel in a plurality of layers with the nut 14 in place on the mandrel. The composite is then cured with the nut held in place. The volume fraction of carbon fibre in the composite is typically in the order of 65%.
The connector 13 further includes an external annular collar 15 which is placed over the outside of the end portion 12 of the composite tube 11 and which in turn is held in place by an end fitting 16, which itself is screwed directly into the internal threaded nut 14, and a load means17 mounted on the end fitting 16.
The collar 15 has a through bore 23 to accommodate the end fitting 16. The end portion 22 of the through bore 23 adjacent the composite tube 11 has an internal frustoconical surface which is substantially parallel with the tapered surface 21 on the nut 14. The nature of the tapered angles employed on the two opposed clamping surfaces of the external collar 15 and nut 14, preferably between 5° and 40° and more preferably between 10° and 25°, provides a clamp load to couple the connector to the end portion 12 of the composite structure and to transmit the working load through to the composite tubular structure 11. The taper and flare angles in the present example are 10°. The other end portion 24 of the through bore 23 comprises a larger diameter portion 24 forming an annular shoulder 25 within the collar 15.
The end fitting 16 has an elongated screw threaded shank 20 which engages the nut 14 and is provided with a suitable manner of joint 26 for connection to a further component (not shown). In this case the joint 26 is a diametral bore for accommodating a clevis pin, but any other suitable joint may be provided on the end fitting, for example the ball of a ball and socket joint, a universal joint etc.. The end fitting 16 has a radially outwardly projecting annular flange 27 located midway along its length which has an axially extending cylindrical sidewall 28 thereon. The sidewall 28 extends away from the collar 15 and forms a cavity for housing the load means 17.
The load means 17 comprises a plurality of set screws 29, preferably six but any number may be provided as is desired, mounted on the flange 27. The screws 29 are mounted in screw threaded holes 31 circumferentially spaced around the flange 27. The end fitting 16 when screwed into the nut 14 is locked in position by screwing the set screws 29 into abutment with the shoulder 25 and a clamping force is generated by rotation of the set screws to increase the axial spacing the flange 27 from the collar 15. Each screw is tightened in stages to a set torque load, in this example to about 15-16 kN. With the end fitting 16 screwed directly into the internal threaded nut 14, the force pulling the internal threaded jut 14 out of the tubular structure is reacted against the clamping load generated by the collar 15 against the tapered end portion 12 of the composite. The subsequent interface between the tubular composite structure and connector 13 is made resistant to fatigue and fretting
by the magnitude of the pre-load generated, making the system tolerant of dynamic loading. A suitable pre-load should be greater than the expected tensile and compressive loads to be transmitted through the control shaft. A suitable pre-load for the present control shaft/rod is about 80 kN .
The control shaft 10 formed by the connectors 13 and composite tube 11 performs over a wide range of temperatures, from cryogenic to elevated and may form a control shaft of the type of the type used in aircraft wings for the operation of flaps.
The control shaft 10 permits adjustment of its overall length. This is advantageous in use of the shaft 10 as the location of the fixed points within a surrounding component structure to which the shaft 10 may be mounted, will be subject to a certain tolerances. The length of adjustment within the assembled composite tube and connector is controlled by how far the screw threaded shank 20 of the end fittings 16 may be screwed into or out of the nut 14 Adjustment is permitted by slackening the screws 29. After adjustment to a desired length, the 'slack' left between the end fitting 16 and the external collar 15 is then taken up by the tensioning screws 29.
For a control shaft having a connector 13 at each end as shown in Fig. 3, then a left hand thread may be provided at one end of the tubular structure, and a right hand thread at the other. By constraining the end fittings it will then be possible to rotate the composite tubular structure clockwise or anticlockwise to extend or contract the
overall length of the shaft. Once again, when the desired length has been achieved, the tensioning screws will be torqued up to take out any play rendering the assembly rigid and ready to take the designed loading.
Claims
1. A connector for connecting a composite tubular shaft to another component and which comprises a screw threaded nut the outer surface of which is shaped to receive in use composite material applied around the nut in a green state during tube manufacture, an annular collar for placement over the nut and composite material, a screw threaded end fitting which engages the screw thread within the nut, and a load means in use axially moving the collar relative to the end fitting to exert a clamping load onto the composite material surrounding the nut.
2. A connector as claimed in Claim 1 wherein the external surface of the nut is substantially ovoid.
3. A connector as claimed in Claim 2 , wherein the external surface of the nut comprises two back to back frustoconical surfaces so that the composite is flared outwardly and tapered inwardly around the nut.
4. A connector as claimed in Claim 3, wherein the frustoconical surfaces are inclined at between 5° and 40° to the axis of rotation of the nut.
5. A connector as claimed in any one of Claims 1 to 4, wherein the external surfaces of the nut are serrated or otherwise roughened to increase frictional resistance to rotational movement between the nut and tubular composite.
6. A connector as claimed in any one of Claims 1 to 5, wherein the collar has a through bore to accommodate the end fitting and the end portion of the through bore adjacent the nut has an internal surface which is substantially parallel with the adjacent surface on the nut.
7. A connector as claimed in any one of Claims 1 to 6, wherein the end fitting is provided with an annular flange and the load means acts between the flange and the collar to exert the clamping load on the composite tube.
8. A connector as claimed in Claim 7 wherein the load means comprise a plurality of circumferentially spaced screw means acting between the flange and collar, the clamp force being generated by rotation of the screw means to further increase the axial spacing of the flange from the collar.
9. A connector as claimed in Claim 8 wherein the screw means are bolts or screws mounted on the flange and which abut the collar.
10. A composite tube having a connector according to any one of Claims 1 to 9 fitted to at least one end thereof, the nut being incorporated within an end portion of the tube.
11. A composite control rod comprising a composite tubular body having an end connector according to any one of Claims 1 to 9 fixed to at least one end of the control rod for the transmission of compressive and tensile loads along the rod, wherein the nut is incorporated within an end portion of the composite tubular body, the screw threaded end fitting engaging the screw thread within the nut, and the load means in use axially moving the end-fitting relative to the collar and to exert a clamping load onto the composite material surrounding the nut.
12. A control rod as claimed in Claim 11 , wherein the clamping load exerted on the composite tube between the nut and external collar, is greater than the intended tensile and compressive loads to be transmitted along the control shaft in use.
13. A control rod as claimed in Claim 11 or Claim 12 having a said end connector fixed to each end of the rod.
14. A control rod as claimed in any one of Claims 11 to 14, wherein the overall length of the control rod may be varied.
15. A control rod as claimed in Claim 14, wherein the end filling has a elongate screw threaded shaft and may be adjusted relative to the nut by releasing the clamping load and screwing the end fitting in one direction or the other to reposition the end fitting relative to the nut, and then re-applying the clamping load.
16. A method of attachment of a load transmitting connector to at least one end of a composite tube, wherein in said method there is provided a connector comprising a screw threaded nut the outer surface of which is shaped to receive in use composite, an annular collar, a screw threaded end fitting for engaging the screw thread within the nut, and a load means in use axially moving the end-fitting relative to the collar i and exerting a clamping load said one end, wherein the nut is incorporated within said one end of the tube during tube manufacture, the tube is cured with the nut insitu, the annular collar is placed over said one end, the end fitting is screwed into the nut, and the load means is operated to move the end fitting relative to the collar and clamp said end of the composite tube between the collar and nut.
17. A method as claimed in Claim 16, wherein the clamping load can be set aslis desired.
18. A method as claimed in Claim 16 or 17, wherein the collar is releasably clamped against the tube allowing the end fitting to be adjustably displaced relative to the nut.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/734,794 US9482266B2 (en) | 2007-11-23 | 2008-02-11 | Connector for a tubular composite shaft |
EP08852796A EP2229540B1 (en) | 2007-11-23 | 2008-11-20 | A connector for a composite tubular shaft |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0722933.9 | 2007-11-23 | ||
GBGB0722933.9A GB0722933D0 (en) | 2007-11-23 | 2007-11-23 | Mechanical connection between composite tubular structure and an end fitting of any engineering material |
GB0812801.9 | 2008-07-14 | ||
GB0812801.9A GB2454958B (en) | 2007-11-23 | 2008-07-14 | A connector for a composite tubular shaft |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2009066070A1 true WO2009066070A1 (en) | 2009-05-28 |
Family
ID=38925902
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB2008/003886 WO2009066070A1 (en) | 2007-11-23 | 2008-11-20 | A connector for a composite tubular shaft |
Country Status (4)
Country | Link |
---|---|
US (1) | US9482266B2 (en) |
EP (1) | EP2229540B1 (en) |
GB (2) | GB0722933D0 (en) |
WO (1) | WO2009066070A1 (en) |
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EP3133298A1 (en) | 2015-08-21 | 2017-02-22 | Crompton Technology Group Limited | Connector |
EP3193029A1 (en) * | 2016-01-12 | 2017-07-19 | Crompton Technology Group Limited | Composite tubular structure |
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CN110005693A (en) * | 2019-04-08 | 2019-07-12 | 上海交通大学 | A kind of thin pull rod connection of geometry locking composite material |
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CN110005693A (en) * | 2019-04-08 | 2019-07-12 | 上海交通大学 | A kind of thin pull rod connection of geometry locking composite material |
Also Published As
Publication number | Publication date |
---|---|
US20120060636A1 (en) | 2012-03-15 |
EP2229540A1 (en) | 2010-09-22 |
EP2229540B1 (en) | 2013-02-20 |
US9482266B2 (en) | 2016-11-01 |
GB0812801D0 (en) | 2008-08-20 |
GB0722933D0 (en) | 2008-01-02 |
GB2454958B (en) | 2012-04-04 |
GB2454958A (en) | 2009-05-27 |
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